PROJECT SUMIVIARY (See Instructions): The overarching goal of our proposed project, SuCCESS: Studying Colorectal Cancer: Effectiveness of Screening Strategies, is to develop evidence to inform personalized screening recommendations that maintain most or all of the benefits of intensive screening, minimize risks and costs, and respect patient preferences. Based within Group Health Research Institute (GHRI), the SuCCESS project will draw on a wide array of rich electronic data sources available at Group Health (GH), an integrated health care delivery system in Washington State, to gather information about risk factors, screening patterns, diagnostic procedures, pathology, treatment, and cancer outcomes among GH enrollees. The SuCCESS project will use GH data to describe colorectal cancer (CRC) screening as practiced, including behaviors and effectiveness, and will build on this information to examine the potential for personalized screening regimens. We propose 3 linked projects related to this overall goal. Project 1, Comparative effectiveness of colorectal cancer screening as practiced, will provide information about how screening is practiced, about patient decisions regarding screening modalities, and about the comparative effectiveness of different screening regimens as practiced. Project 2: Personalizing colorectal cancer screening and surveillance, will focus on identifying effective personalized screening regimens based on screening history and other individual risk factors. Project 3, Modeling long-term comparative effectiveness of colorectal screening, will use disease simulation models to predict the long-term effectiveness of different screening and surveillance regimens on botii overall and CRC mortality based on results from Project 1 and Project 2, and will develop a cohort model for CRC that will be freely distributed. Our proposed body of research will provide an important foundation for personalized clorectal cancer screening, and will produce results that are useful to a multidisciplinary audience, including clinicians, patients, policy makers, researchers, and professional medical organizations.